To prepare for the scrums and handfights that football linemen face, Anthony Zettel trained in mixed martial arts over the summer. Someday, perhaps, the Penn State defensive tackle might step into the MMA cage.

"It's basically like football," Zettel said. "A test of wills."

Zettel, a redshirt junior from Michigan, has been testing the wills of opposing offenses quite a bit this season. The Big Ten's leader in tackles for loss has made more stops behind the line of scrimmage than in front, a statistic Massachusetts coach Mark Whipple fears will continue Saturday.

With seven tackles for loss among his 13 this season, Zettel has been "playing out of his mind," the UMass coach said. He's but one reason Whipple doesn't expect the Minutemen to run for many yards against the Nittany Lions at Beaver Stadium.

"Those guys up front are making it happen," Whipple said.

Penn State expected its defensive line to be a strength behind tackle Austin Johnson and ends Deion Barnes and C.J. Olaniyan. But Zettel, who played an active role at defensive end the past two years, was shifting inside, where his pass-rush skills might get squeezed.

So far Zettel has been every bit the force he was outside, where he made eight sacks the past two seasons. Zettel made three tackles in the opener against Central Florida, all for loss, and added three more last week against Rutgers.

The player whom coach James Franklin calls "sudden" and "disruptive" has three sacks, one in each game, and recovered a fumble against Central Florida. On that play, Zettel basically ripped the ball from Knights quarterback Justin Holman while both were on the ground.

After last week's game, in which Zettel made a critical fourth-quarter sack, Rutgers coach Kyle Flood called the tackle "as good as anybody in the country." That's quite a leap for a one-time 250-pound defensive lineman who knew he needed to get better.

As a freshman at Penn State, Zettel played several spots on the scout-team defense, including tackle, where he was simply undersized. "It was rough on the body," Zettel said.

From there, Zettel set about adding 20-30 pounds of muscle to become more physical. He made an impact at end his first two seasons, generating four sacks each year.

After evaluating the defense last winter, Franklin said he wanted to move Zettel inside. The coach had his speech planned, but Zettel came to the meeting ready to ask for the same move.

"I learned, once it's been sold, stop selling," Franklin said.

Coaches raved last spring about Zettel's approach to his new position, which carried into the fall. Still, though he's 6-4, 285 pounds, Zettel feels like opposing teams consider him undersized. And he has used that to his advantage.

Franklin raved about Zettel's spin move, which he used to produce a fourth-quarter sack against Rutgers. Zettel also considers his lateral quickness a key to beating offensive linemen who are 20-30 pounds bigger.

"He was an athletic defensive end, but by moving him inside, he's now becoming an even more athletic defensive tackle," Franklin said. "… His tenacity is unbelievable. His quickness is unbelievable and he's not the biggest guy. I mean, he's big enough at 285 pounds, but there are much bigger defensive tackles."

Those bigger defensive tackles often win interior battles with size. Zettel understood his quickness wouldn't withstand double-teams, so he added MMA training and kickboxing to his repertoire.

A summer of that work has helped him use his hands to get off blocks and "get off the guy before he hits you." Maybe someday, after football, he'll try it for real.

"It's been in the back of my mind to pursue it after football is done," Zettel said. "It's a hobby, but if I get good at it, then I might want to pursue it further."